The present invention relates to a cold storage or hold-over pack for use with a refrigeration system and more particularly to a portable hold-over pack for use with existing refrigeration systems on, for example, marine vessels, recreational vehicles, and household refrigeration systems.
Eutectic holding plates are well known in the art. These devices are referred to as "holding plates" or "holdover plates" because they provide continued cooling action to a compartment once their associated refrigeration systems are turned off. These conventional holding plates, however, have freon or refrigeration coils located internal to their structure. In other words, the refrigerant flows through tubes or passages within the holding plate. In use with a refrigeration system, the conventional holding plate actually comprises a portion of the freon cycle. If any damage occurs to these holding plates, the entire volume of refrigerant must be emptied or evacuated from the system. This process inevitably leads to some refrigerant being released into the atmosphere, which is a major ecological concern.
Industrial and commercial freon leaks, including leaks from residential and marine refrigeration systems, are believed to be a major contributor to the deterioration of the earth's ozone layer. Federal policies have been enacted to curtail the discharge of refrigerant into the atmosphere and, as a consequence thereof, refrigeration and air conditioning businesses will need expensive vacuum recovery systems to minimize the discharge of refrigerants into the air.
The conventional holding plates also have the disadvantage that, in order to repair or replace the holding pack, the entire refrigeration system must be shut down and the refrigerant evacuated from the system prior to breaking into the system to change out or repair the holding pack. Additionally, the system is limited to the number of holding packs initially configured in the system. In other words, another holding pack could not be added to the system once operation has begun without shutting down the system and evacuating the refrigerant.
The conventional holding plates are further limited in that they are generally sealed eutectic systems. In other words, the plate is initially filled with a certain eutectic solution and thereafter permanently sealed. Different eutectic solutions have different thermal characteristics. A particular eutectic solution can be chosen for its desired freezing point depending upon the purpose the holding plate is to be used for. The eutectic solution used in a cold storage holding plate, for example, freezes at a much higher temperature then the eutectic solution used in a freezer holding plate. With the conventional plates, once the plate is initially filled and installed in the refrigeration system, it is generally limited to use as a particular type of holding plate depending on the particular eutectic solution it was initially filled with, for instance a cold storage plate only.
Examples of commercially available conventional holding plates include the Cold-Cel.RTM. by Dole Engineering; the Coldbank.TM. by Adler-Barbour offered in a variety of sizes; and the Cold Plates offered by Fleming Marine USA, Inc.
Examples of some known prior art devices are shown in the following patents: U.S. Pat. No. 2,416,015 to McGuffey, U.S. Pat. No. 2,795,114 to Kleist, and U.S. Pat. No. 2,769,310 to Strickland refer to holding plates or heat exchange devices in general; U.S. Pat. No. 2,188,349 to Heideman, U.S. Pat. No. 2,248,607 to Cooper, and U.S. Pat. No. 3,845,638 to Apple et al. pertain to holding plate refrigeration systems in general; U.S. Pat. No. 3,721,104 to Adler references a marine refrigeration and cool storage system employing a container with a eutectic solution disposed therein and means for freezing the solution; U.S. Pat. No. 4,114,396 to Rickert discloses a refrigeration system evaporator coil having a series of heat exchange surfaces; and U.S. Pat. No. 2,875,595 to Kleist discloses a eutectic blower system for refrigerator spaces.